Tehran University of Medical Sciences Acta Medica Iranica 0044-6025 42 1 2004 02 15 31 35 M. H. Pipelzadeh A. A. Hemmati A. Dezfulian M. H. Koochek A. Rostami 2015 09 28 The exact role of the epithelial lining of the trachea in modulating the bronchial tone is controversial. The present study was an attempt to verify the role of both prostaglandins and mast cells in the acute phase of acid inspiration in rat. Four groups (n = 6) of N. Mari rats were employed. The first group was used as placebo control, and normal saline was injected. To the second group hydrochloric acid (25 µl) with pH of 1.3 was injected into the trachea through the criothyroid membrane. The third and fourth groups were pretreated for three consecutive days either with indomethacin (10 mg/Kg) or nebulized sodium cromoglycate (20 mg/Kg), 1 hour prior to installation of the acid. Three minutes after instillation of acid, the trachea was removed. The tracheal spirals were prepared and immediately suspended in an organ bath containing Tyrode’s solution. Dose response curves to acetylcholine (10-9 to 10-3M) were constructed. The results showed that the responses to acetylcholine in the acid treated trachea were significantly (P https://acta.tums.ac.ir/index.php/acta/article/view/2685 https://acta.tums.ac.ir/index.php/acta/article/download/2685/2667